Simulation Study of a Turbofan Engine With Ammonia As Energy Carrier

The shift from a conventional Jet-A aircraft engine to a zero-carbon emission engine such as an ammonia-cracked hydrogen combustion engine is integral to decarbonizing aviation. This paper proposes a novel design for integrating ammonia cracking into a high-bypass, two-shaft turbofan engine, like the one used in the Boeing 737 Max, modeled as a steady-state Brayton cycle. The design addresses the hydrogen storage issue while improving ammonia’s combustion characteristics and minimizing NOx generation. First, a baseline turbofan engine model fueled by Jet-A is validated against parameters from existing literature. Subsequently, an ammonia cracker-combustor interloop is incorporated into the model, thus replacing Jet-A with an ammonia-hydrogen blend. Heat for ammonia cracking is supplied by the combustion chamber. The ammonia conversion rate and, ultimately, the amount of hydrogen produced, impacts the overall system efficiency. Therefore, cracking conditions are optimized for a high conversion rate. Finally, the ammonia-based design was thermodynamically analysed in the cruising operation mode. Aspen Plus software is selected for the entire simulation due to its reliable thermodynamic properties and calculations. In essence, this model aims to seamlessly integrate the ammonia cracker-combustor flow path into the turbofan engine while evaluating the required fuel consumption and system performance relative to the Jet-A model.